Drying apparatus,particularly for green crops



June 23, 1970 A. T. NIELSEN 3,516,172

DRYING APPARATUS, PARTICULARLY FOR GREEN CROPS Filed May 27. 1968 FIGJ United States Patent r 3,516,172 DRYING APPARATUS, PARTICULARLY FOR GREEN CROPS Alfred Thygesen Nielsen, Lyngbakkevej 8, Sollerod pr. Holte, Denmark Filed May 27, 1968, Ser. No. 732,158 Claims priority, application Denmark, June 1, 1967, 2,883/ 67 Int. Cl. F26b 17/32 US. Cl. 34-136 2 Claims ABSTRACT OF THE DISCLOSURE In a drying apparatus comprising a preferably rotary drum operating with an axial flow of heated gaseous fluid from which the dried solid material shall be separated, this separation is made possible by a piece of netting allowing the gaseous fluid to pass but retaining the solid matter. This solid matter is continuously removed from the netting by means of at least one suction nozzle arranged adjacent the inner side of the netting and operated by a suction source or vacuum pump from which the solid mater may be fed to a briquetting press.

This invention relates to a drying apparatus, particularly for green crops, and of the known type comprising a drum, which is arranged for substantially axial throughflow of heated drying air and adjacent the inlet for the drying air comprises means for admitting the material to be dried, which during progressive drying is carried along by the flow of drying air in the direction towards the outlet end of the drum and is then separated from the drying air.

Most drying apparatuses falling under this category and used in practice are of the so-called semi-pneumatic type in which the drum rotates comparatively slowly around its substantially horizontal axis and on its inside is provided with vanes or fins which lift the material or the goods to be dried from the bottom of the drum and let it drop again down through the flow of drying air which during this activity causes a certain fractioning of the material, the particles of the latter which under the given circumstances can manage with the shortest stay in the drying drum moving faster towards the outlet end of the latter than the particles, e.g. parts of stalks or straw, demanding a stay of a longer duration. In practice, this fractioning is of great importance, making possible a substantially uniform drying of the different components of the raw material. With a view to controlling the drying process, both the quantity of goods to be dried and the amount and temperature of the drying air can as a mile be varied, e.g. in dependence on the temperature at one or more measuring points within the drum or at the outlet from the latter.

Drying apparatuses of the type referred to usually operate at a vacuum, a heated flow of air being sucked through the rotary drum, and the final separation of the dried goods from the air is then performed in the way that the total flow of air with its content of dried parts of the material is led through a cyclone separator, from which the air is expelled to the surroundings. This mode of operation requires, inter alia for the separation stage, a comparatively high power consumption, which is mainly due to the fact that the whole amount of air must pass through the cyclone.

The invention aims at providing a drying apparatus which for the same capacity can operate with a considerably reduced power consumption. For this purpose the drum space is bounded towards the outlet end by a netting for retaining the dried goods, and one or more suction nozzles are provided at the inside of this netting Patented June 23, 1970 for removing the goods retained on the netting during relatlve movement between the netting and the suction nozzle.

In this case the separation of the dried goods and the flow of air is thus already effected within the drum, and only a fraction of the total amount of air is sucked out of the drum together with the dried material, while the remaining part of the amount of air, e.g. about can exhaust directly into the atmosphere.

Even if the apparatus may operate at a vacuum as explained above, it will as a rule be most expedient to use an elevated pressure, inter alia to facilitate the sucking-01f of the dried goods from the netting. This sucking-off constantly ensures such a cleaning of the netting that the latter will not block the passage of the flow of drying air.

The drying apparatus may expediently be of the semipneumatic type referred to above, but the drying drum may also be stationary. If in this case it is mounted with its axis horizontal or substantially horizontal, rotary vanes may in a known manner he used for whirling up the goods to be dried in the drum.

In a preferred embodiment of the drying apparatus according to the invention, where the latter comprises a rotary drum, the netting is incorporated as end wall in the drum, and the suction nozzle or each suction nozzle is constituted by a slotted pipe extending from the periphery of the end wall to its centre and being at the latter connected to a sucking-0E pipe passing through the end wall.

In this embodiment the drying apparatus is particularly simple as regards its constructional design, inter alia because the rotation of the drying drum can be utilized for providing the relative movement between the netting and the suction nozzle, so that the latter may be stationary.

A preferred embodiment of the invention will now be more fully explained with reference to the accompanying drawing in which:

FIG. 1 is a rather diagrammatic side elevation, partially in section, of the apparatus,

FIG. 2 a partial section on line IIII in FIG. 1, and

FIG. 3 a partial plan view of FIG. 1.

The apparatus shown comprises a drum 1 which is mounted with its axis horizontal or substantially horizontal and which can rotate around this axis. The supporting and driving means are not shown in the drawing.

The left end of the drum extends into a housing 2 which is supposed to comprise an inlet for the goods to be dried, e.g. new-mown grass, and a fan for effecting a flow of drying air through the drum 1. With a view to heating the drying air the housing 2 may furthermore comprise a combustion chamber of a suitable construction.

The right end wall of the drum 1 consists substantially of a piece of netting 3 stretched between an inner ring 4 and an outer ring 5. This outer ring is in a suitable way connected to the outer shell of the drum 1, and the inner ring 4 encloses in a sliding manner a stationary closing plate 6, through which a pipe duct 7 extends into the drum 1. The part 8 of the pipe duct located within the drum forms a slotted pipe, see FIG. 2, the slot of which faces the netting 3, and as shown in FIG. 3 the other end of the pipe 7 is connected to the inlet of a fan 9 which is driven by a motor 10 and the outlet 11 of which can lead to an apparatus for compressing the dried material which through the slotted pipe 8 is sucked off the inside of the netting 3.

What I claim is:

1. A drying apparatus, particularly for green crops, comprising a drum arranged with its axis in a substantially horizontal plane and having an inlet end and an outlet end, means for producing a substantially axial through-flow of heated drying air from said inlet end admitting .goods to be dried into said .drum,-and-meansfor separating the dried goods from the flow of drying air, said separating means comprising a netting for retaining the dried goods while allowing the drying-air to pass through said outlet end, at least one suction nozzle arranged on the upstream side of said netting for removing the goods retained thereon, and means for moving said netting relative to said suction nozzle.

2. A drying apparatus as claimed in claim 1, and wherein said drum is rotatable around its substantially horizontal axis, said netting forming an end wall of the drum adjacent its outlet end, and said suction nozzle constituted by a stationary slotted pipe extending fromthe periphery of? saidend- Wall to its center-and connected to a discharge pipe passing through said end wall at its center point.

ReferencesCited UNITED STATES PATENTS EDWARD J. MICHAEL, Primary Examiner 

